Recently developed GC/MS and LC/MS methods for determining NSAIDs in water samples

Pharmaceuticals have become major targets in environmental chemistry due to their presence in aquatic environments (following incomplete removal in wastewater treatment or point-source contaminations), threat to drinking water sources and concern about their possible effects to wildlife and humans. Recently several methods have been developed for the determination of drugs and their metabolites in the lower nanogram per litre range, most of them using solid-phase extraction (SPE) or solid-phase microextraction (SPME), derivatisation and finally gas chromatography mass spectrometry (GC-MS), gas chromatography tandem mass spectrometry (GC-MS/MS) and liquid chromatography electrospray tandem mass spectrometry (LC-ES/MS/MS). Due to the elevated polarity of non-steroidal anti-inflamatory drugs (NSAIDs), analytical techniques based on either liquid chromatography coupled to mass spectrometry (LC-MS) and gas chromatography coupled to mass spectrometry (GC-MS) after a previous derivatisation step are essential. The most advanced aspects of current GC-MS, GC-MS/MS and LC-MS/MS methodologies for NSAID analysis are presented.     

Two main utility-sharing methods in joint businesses: A discussion

We compare two methods of sharing costs or profits among agents in cooperative games: the well–known proportional rule and the Shapley value. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Automatic gain control of semiconductor laser amplifiers

A new approach to automatic gain control has been demonstrated and a signal polarization independent operation over a 35-nm wavelength range at a gain level of 17 dB has been obtained.     

Transforms and Minors for Binary Functions

We introduce a family of transforms that extends graph- and matroid-theoretic duality, and includes trinities and so on. Associated with each such transform are λ -minor operations, which extend deletion and contraction in graphs. We establish how the transforms interact with our generalised minors, extending the classical matroid-theoretic relationship between duality and minors: ${(M/e)^* =M^* \backslash e}$ . Composition of the transforms is shown to correspond to complex multiplication of appropriate parameters. A new generalisation of the MacWilliams identity is given, using these transforms in place of ordinary duality. We also relate the weight enumerator of a binary linear code at a real argument < –1 to the transform, with parameter on the unit circle, of a close relative of the indicator function of the dual code. This result extends to arbitrary binary codes. The results on weight enumerators can also be recast in terms of the partition function of the Ising model from statistical mechanics. Most of our work is done at the level of binary functions ${f : 2^E \rightarrow \mathbb{C}}$ , which include matroids as a special case. The specialisation to graphs is obtained by letting f be the indicator function of the cutset space of a graph.     

Synthesis of apocarotenoids by acyclic cross metathesis and characterization as substrates for human retinaldehyde dehydrogenases

A new synthesis of three apocarotenoids, namely 14′-apo-β-carotenal, 12′-apo-β-carotenal and 10′-apo-β-carotenal, has been achieved that is based on the acyclic cross-metathesis of the hexaene derived from retinal and the corresponding partners. These compounds can be enzymatically converted to their carboxylic acids by the human aldehyde dehydrogenases involved in retinaldehyde oxidation. Their kinetic parameters suggest that these enzymes might play a role in the physiological metabolism of apocarotenoids.